The invention relates to improving the heat storage capacity of a regenerator, and more particularly to creating transverse flow within a regenerator in which the primary flow is through longitudinally extending, adjacent flues in a regenerator checker packing.
One type of regenerator packing includes heat retaining refractory pieces that are stacked so as to define a checkerwork having a series of substantially parallel flues or open passgeways extending through the checkerwork. During the furnace exhaust phase, hot exhaust gases pass from the furnace through the checkerwork flues where heat is absorbed from the exhaust gases by the packing. Heat retained by the packing is then recovered during the furnace firing phase when combustion air passes in the reverse direction through the flues where it is preheated by the retained heat of the regenerator bricks before passing to the combustion means firing the furnace. The amount of heat recovery possible with a regenerator system depends in large part upon the surface area of refractory material available for heat transfer, but surface area may not always be effectively utilized.
To allow for expansion when heated, generator checkerworks are generally constructed with some open space between refractory pieces, which spaces may or may not close completely when the regenerator is heated. In packing arrangements where these spaces remain, they may provide passageways between flues, but is has been observed that very little, if any, gas flows through these passageways, and therefore the surfaces of these passageways are not effectively utilized for heat transfer.
It is theorized that the temperature of the relatively stagnant air in these transverse passageways tends to equilibrate with the surrounding refractory material, whereby the temperature difference, and thus the heat transfer, is less than if gases from the main stream were actively flowing through the passageways.
Typically, the checker packing is comprised of refractory bricks having rectangular faces, and the transverse passageways comprise spaces between opposed faces of adjacent bricks. Other types of regenerator packing are built from complex, interlocking shapes of refractory, such as chimney blocks of the type manufactured and sold by Veitscher Magnesitwerke, A. G., Vienna, Austria. This type of block is available with an open center portion, so that when stacked, the individual blocks and spaces between blocks define a series of parallel flues. Chimney blocks with transverse passages between the flues are also available, but relatively stagnant conditions would also be expected in these passages.
Various other irregular shapes for checkerwork blocks and bricks have been proposed for increasing turbulence of gases flowing through checker packing, such as those taught in U.S. Pat. No. 2,532,112 to Mackensen, U.S. Pat. No. 1,745,113 to Odell, U.S. Pat. No. 1,574,584 to Lindner and U.S. Pat. No. 2,527,429 to Kennedy. Although acceptable for increasing turbulence in flowing gases, these patents are directed in general to increasing turbulence in gases which flow longitudinally through the regenerator, i.e., in the dominant gas flow direction through the flues.
Although a variety of refractory brick configurations have been proposed for furnaces where combustion occurs within the brick arrangement, such as those taught in U.S. Pat. No. 2,785,212 to Begley and U.S. Pat. No. 1,381,625 to Finch, these bricks are designed primarily for retaining gases within the furnace until complete combustion occurs, rather than for increasing flow of gases therethrough.
It would be advantageous to have a regenerator brick or block arrangement which would increase transverse flow of gases through passages between checker packing flues for improved heat transfer within the regenerator.